U.S. Sen. Jeanne Shaheen and U.S. Rep. Annie Kuster want the federal government to clear the way for Concord’s aging, deteriorating Sewalls Falls Bridge to be replaced.

The two New Hampshire Democrats sent a letter Tuesday to Anthony Foxx, the new U.S. secretary of transportation, urging the Federal Highway Administration to “utilize all existing authority to expedite this critical effort” and approve the project “without delay.”

Replacing the 1915-era bridge has been on the city’s agenda since the 1990s. In February, the City Council voted to tear down the bridge and build a new two-lane span across the Merrimack River, abandoning a 2006 plan that would have involved rehabilitating the existing bridge and building a second span next to it.

The FHWA is still reviewing the new plan, which relies on federal aid to cover 80 percent of the project’s cost. A so-called Section 106 review is required to examine alternatives to demolition, since the bridge qualifies for the National Register of Historic Places.